Electric and hybrid motor vehicles, notably, usually have a first voltage source supplying a primary circuit with direct current and a second voltage source consisting of a battery, called the auxiliary battery, supplying a secondary circuit forming the auxiliary network, said primary and secondary circuits being connected to one another by a non-reversible voltage-controlled current source, usually consisting of a DC/DC voltage converter.
Hybrid vehicles of the “micro-hybrid” type have two power sources incorporated in the auxiliary network, namely a non-reversible voltage-controlled current source consisting of an alternator, and a voltage source consisting of an auxiliary battery.
The auxiliary network of any of these vehicles is therefore supplied by an auxiliary battery and by a non-reversible voltage-controlled current source, so that, if there is a faulty connection of the auxiliary battery, the power supply to the auxiliary network is provided by the current source.
Developments have now taken place with a view to reducing energy consumption, by causing the supply from the current source to be cut off in specific operating states of vehicles; consequently, in order to provide these cut-offs without cutting off the whole power supply, it is essential to be able to ensure that there is no faulty connection of the auxiliary battery.